Continuing advances in integrated circuit technology have led to an ongoing need to decrease minimum feature sizes. This scaling down of integrated circuits has resulted in the use of ultra-thin gate oxide films. Such films, which may be less than 20 Å thick, are often subjected to nitridation to improve the resistance of the film to dopant penetration, to decrease the leakage current of transistors that incorporate these films, and to improve the resistance to radiation damage of devices incorporating these films. A variety of film nitridation processes are currently known to the art, including thermal anneal processes, ion implantation processes, and plasma nitridation processes (both remote and in situ).
The rate and degree of nitridation in a typical nitridation process usually depends on a number of variables, such as temperature, plasma power, gas flow rates, chamber pressure, and the like. Regardless of the type of nitridation process used, it is typically important to accurately control both the depth and the degree of nitridation. In the past, this has frequently been accomplished through the use of timed techniques. While such techniques can provide adequate nitridation control in some applications, these techniques do not provide real-time quantitative information on the plasma properties as would be useful to improve process control in many applications.
There is thus a need in the art for a method for providing real-time quantitative feedback on plasma properties in plasma treatment processes. There is further a need in the art for semiconductor fabrication equipment which utilizes such a process. These and other needs may be met by the devices and methodologies described herein.